1. Technical Field
The present disclosure relates to apparatus and methods for implanting tissue anchors and, more particularly, to apparatus and methods for implanting expandable tissue anchors.
2. Background of Related Art
During surgery it is often necessary to attach prosthetic implants or soft tissue such as muscle tissue, ligaments, or tendons to hard tissue such as bone. Various types of surgical fasteners are employed for accomplishing this function, including staples, screw and washer systems, suture anchoring devices, and tissue anchors.
The first of these types is illustrated in U.S. Pat. Nos. 4,454,875 and 4,570,623, which show metal staples with spikes on the underside of the crosspiece to secure ligaments.
Fasteners included in the second of these types are available as screw-washer combinations wherein the screw is fabricated from a surgically suitable metal, such as titanium or stainless steel alloy, and is usually of self tapping design. The washer can have distally pointing spikes and a central aperture through which the screw is disposed.
Suture anchors are adapted to be inserted into predrilled holes in bone and can be made of bioabsorbable material. U.S. Pat. No. 5,354,298 to Lee et al. discloses a two-piece suture anchor and an installation tool therefor. The suture anchor has a setting pin which is slidably connected to a socket having expandable legs. When the setting pin is retracted into the socket by being moved proximally (i.e. by pulling on the suture) the socket legs are radially splayed to secure the suture anchor in the hole in the bone.
Expandable tissue fasteners have bodies which directly fasten the soft tissue to bone, for example by means of a head portion with distally pointing teeth or spikes, rather than by means of a suture. For example, see U.S. Pat. No. 5,013,316 to Goble et al., which discloses a soft tissue anchor having a footing stud with self tapping threads for insertion into a hole in bone, and a tack portion which engages the footing stud. The tack portion has a broad head with spikes for securing soft tissue. U.S. Pat. No. 5,129,906 to Ross et al. discloses a cannulated bioabsorbable tack having annular ribs for attaching soft tissue to bone. Other fasteners include expandable portions which are inserted into a hole in bone and expanded therein to secure the fastener. For example, the fastener can include a body portion which is inserted into the bone and a setting pin which expands the body portion.
Expandable tissue fasteners adapted for use in minimally invasive surgical procedures (e.g. arthroscopic procedures) are employed, for example, in the repair of shoulder and knee injuries. In such procedures the operating instrumentation is usually deployed through a long, narrow cannula inserted through a small incision in the skin.
What is needed is an apparatus and method for conveniently applying an expandable tissue fastener, especially in minimally invasive surgical procedures.